Little effect of ordinary antihypertensive therapy on nocturnal high blood pressure in patients with sleep disordered breathing

The antihypertensive effects of four different antihypertensive medications (beta-blocking agent, atenolol 50 mg; calcium-antagonist, isradipine SRO [slow release] 2.5 mg; diuretic, hydrochlorothiazide [HCTZ] 25 mg; and angiotension converting enzyme-inhibitor, spirapril 6 mg) on obese patients with sleep disordered breathing and hypertension were compared by the ambulatory blood pressure measurement (ABPM). Eighteen patients were randomized in a double-blind, crossover fashion to receive each of the four different medications for 8 weeks. ABPM was performed at baseline and after an 8-week treatment with these medications. A 2- to 3-week washout period occurred both at baseline and between each of the four medications. Three patients were omitted from statistical analysis because of technical problems of ABPM. Atenolol, isradipine SRO, and spirapril decreased significantly (P < .01) the mean 24-h systolic blood pressure, whereas HCTZ did not. The mean 24-h diastolic blood pressure decreased significantly after all four medications: 12 (SD +/- 14) mm Hg with atenolol, 7 (SD +/- 10) mm Hg with isradipine SRO, 3 mm Hg (SD +/- 14) with HCTZ, and 6 (SD +/- 15) mm Hg with spirapril (P < .01). During nighttime none of the medications reduced the mean diastolic or systolic blood pressure significantly. According to the 24-h blood pressure curve the influence of these four medications during the whole measurement period was not similar. Atenolol and spirapril lost their antihypertensive effect during the early morning hours. The antihypertensive effect of HCTZ varied markedly from hour to hour. The trough-to-peak ratio of no medication was >0.50. Negative correlation was observed between the apnea time and the mean systolic 24-h (r = -0.604, P = NS) and the mean systolic nocturnal blood pressure change (r = -0.590, P = NS). Our study revealed that the daytime high blood pressure was quite easily controlled by the ordinary monotherapy in these patients with partial upper airway obstruction and hypertension. Instead none of the medications used decreased nocturnal high blood pressure markedly. (C) 1998 American Journal of Hypertension, Ltd.